Aeration tank

Abstract

An aeration tank comprising a mixing vessel having starting and end zones. The mixing tank has water-jet aeration columns and communicates with a sludge separator provided with an outlet of recyclable sludge communicable with a circulation pump connected through a pressure pipe line to the aeration columns. There is also provided a regeneration chamber communicated with the outlet of recyclable sludge of the sludge separator and with the end zone of the mixing vessel, and a chamber for deoxygenation of the sludge medium having an inlet of waste water and communicating with the regeneration chamber and with the starting zone of the mixing vessel. A suction pipeline of the pump communicates with the chamber for deoxygeneation of the sludge medium and with the starting zone of the mixing vessel. Each aeration column has a converging inlet portion in which the pressure pipeline of the pump having a nozzle is introduced, and an adjacent portion of invariable cross-section accommodating a disperser of oxygen-containing gas. The inlet portion has ports and is provided with a gas-trapping casing immersed in the sludge medium so as to isolate the inlet portion from the outside.

What is claimed is: 
     
       1. An aeration tank comprising: a mixing vessel having a starting zone and an end zone;   counterflow-type water-jet aeration columns disposed in the starting zone of said mixing vessel;   inlet means for admitting to said mixing vessel waste water and activated sludge, this means being disposed in the starting zone of said mixing vessel;   an outlet of sludge medium disposed in the end zone of said mixing vessel;   a thin-layer sludge separator adapted for separating recyclable sludge and sludge water from the sludge medium and having an inlet connected to said outlet of the mixing vessel for feeding sludge medium thereinto, and outlets of waste water and recyclable sludge;   dispersers of oxygen-containing gas disposed in said mixing vessel;   a chamber for regenerating sludge medium communicable with the outlet of recyclabe sludge of said sludge separator and with the end zone of said mixing vessel;   dispersers of oxygen-containing gas disposed in said regeneration chamber;   a chamber for deoxygenation of sludge medium communicable with said regeneration chamber and having an inlet for admitting waste water thereto and an outlet communicable with the starting zone of said mixing vessel;   dispersers of oxygen-containing gas disposed in said deoxygenation chamber;   a circulation pump;   a suction pipe of said circulation pump having two branches, one of the branches communicating with the starting zone of said mixing vessel, the other communicating with said chamber for deoxygenation of sludge medium;   a pressure line of said circulation pump connected to said aeration columns;   a nozzle secured on said pressure line of said circulation pump;   said aeration columns having each:   a converging inlet portion in an upper section of said aeration column, fitted to this portion being said pressure pipeline of said circulation pump provided with the nozzle;   a diverging outlet portion in a lower section of said aeration column;   a portion of continuous cross-section interposed between said inlet and outlet portions;   a disperser of oxygen-containing gas disposed in said portion of continuous cross-section;   ports provided in said outlet portion;   gas-trapping isolating casing secured on said pressure pipeline of said circulation pump so that its free end is immersed in sludge medium to isolate said inlet portion from the outside;   at least one source of oxygen-containing gas communicating with said dispersers of oxygen-containing gas.   
     
     
       2. An aeration tank as defined in claim 1, in which the largest cross-sectional area of the outlet portion is 2 to 5 times the cross-sectional area of the portion of continuous cross-section. 
     
     
       3. An aeration tank as defined in claim 2, in which a free edge of said isolating casing has a diameter 1.5 to 3 times the largest diameter of the outlet portion. 
     
     
       4. An aeration tank as defined in claim 3, in which the length of said diverging outlet portion is between 0.5 and 0.75 times the length of the entire aeration column. 
     
     
       5. An aeration tank as defined in claim 4, in which said outlet portion is provided with at least one jet-guiding tapered perforated hood arranged concentrically with said outlet portion and having the same taper as said outlet portion.